ABSTRACT
<b>Purpose:</b> The purpose of this study was to determine whether the impact on the body during landing in dancers is less than in non-dancers by using accelerometers and motion analyzer.<b>Method:</b> Eleven ballet dancers and 11 non-dancers participated in this study. Each subject was instructed to perform 3 types of landing from a height of 30cm: <i>landing, silent landing</i> and <i>raise up landing.</i> Markers were put on the iliac crest, greater trochanter, knee joint, lateral malleolus. The peak vertical and horizontal accelerations of the lumbar, peak vertical acceleration of the greater trochanter and the peak flexion angles of the hip and knee joints were measured after the trials.<b>Result:</b> In the <i>raise up landing,</i> the peak vertical acceleration of the lumbar region in dancers was less than that in non-dancers (p < 0.01), and the peak knee-flexion angle in dancers was greater than that in non-dancers (p < 0.01). There were no differences between the peak hipflexion angles of dancers and non-dancers.<b>Conclusion:</b> The impact on the lumbar during <i>raise up landing</i> was less in dancers. In <i>raise up landing,</i> the trunk tends to be fixed when the dancer stands upright. Moreover, dancers attenuated the shock to the lumbar region by increasing the knee-flexion angle to a greater extent than the non-dancers did. This result may indicate the importance of the knee joint flexion in attenuating the shock during landing and show that dancers excel in using their knees flexibly.
ABSTRACT
A study was conducted to investigate the cushioning effects of lower extremity functions on shock attenuation during landing on one leg.<BR>Optical methods were used to investigate the cushioning effects of lower extremity functions, since these facilitated the quantitation of kinematic variables such as angle, change in angle, position, displacement and velocity during the landing. The subjects were 5 healthy students ranging in age from 21 to 24 years. Ground reaction force (GRF) was measured with a force platform. The impact force peaks showed vertical force-time averages for 1 subject landing on one leg or two legs for 10 trials each from a height of 10cm.<BR>The peak/body weight of impact force of GRF upon landing was attenuated by the cushioning effects of the lower extremity functions, i. e. bending of the knee and ankle joints, more effectively on two legs than on one.<BR>Supination and pronation of the ankle joint influenced the impact force peaks, and the results of this experiment demonstrated significant difference between the number of discharge bursts of leg muscles upon landing on one leg and those landing on two, the former being higher.